The science of Heating an aquarium.

The water in a marine aquarium must be maintained at a reasonably constant temperature.  Temperature is important if fish and invertebrates from tropical coral reefs are to survive. Animals collected from your local coast can be maintained at the temperatures that occur naturally where you live. In some places, measures to cool down the tropical aquarium may be required, particularly during summer months.

Types of aquarium heating equipment

There are many different types of heaters available. The two main heaters types are fully submerged and partially submerged.  

Both heaters work well however the submerged type can be hidden better. You can select the appropriate size heater by using the formula of 5 watts per gallon of water. By using this formula a 20-gallon tank will need a 100-watt heater and a 30-gallon tank will require 150-watt heater.

The other type of heater, which is getting more popular, is the in-line heater.  The in-line heater goes in to the water filter and heats the water as it returns to the tank. This heater is a good choice if you want your heater out of view.

Heating equipment may also be incorporated within the water treatment compartment (or sump) of a built-in total system. This can make more efficient use of your heater.  This is because it is heating a smaller body of water at any one time. For larger systems use of heating elements housed in a sleeve, which can be plumbed directly into the pipework of the water circulation system, are recommended.

heating aqaurium

When measuring the water temperature, you can use any type of aquarium thermometer.  Thermometers all tend to be made either from glass or a suitable plastic. You can also choose from a variety of digital electronic thermometers designed for aquarium use.

Controlling and conserving heat

In a standard aquarium heater, the built-in thermostat controls the supply of electricity to the heating element.  This is done by  sensing the temperature of the water. This reading is achieved by means of a bimetallic strip that bends and straightens, making and breaking contact as the temperature changes, or by microchip circuitry.

Microchip thermostats are normally a separate unit from the heating element. The temperature control is achieved by a probe in the water that sends a message back to the thermostat.  This in turn regulates the power to the heating element. Large, ready-built complete systems often use these high-tech thermostats however, they are not so widely used in the average home aquarium. For most tropical marine aquariums, the ideal temperature is around 75°F (24°C).

The heaters are usually factory preset to the ideal temperature and can be adjusted a few up or down. External thermostat units can be either analogue or digital. Analogue units are set manually, but digital models allow you to programme a variety of temperature parameters and often have automatic features.  One of these features can be emitting an alarm if the temperature gets too high or too low.

Some heaters include a display which records the maximum and minimum temperature reached in a time period.  This is alongside showing the current temperature. The result of this is that digital units can offer the degree of control and accuracy that will provide extra protection for aquarium subjects and peace of mind for you too.

Changing the water temperature

To avoid stressing the fish, always adjust the water temperature very slowly and gradually particularly if you are lowering the temperature. This is because fish are less tolerant of a sudden drop in temperature rather than they are of a rise in temperature. Such adjustments could trigger a disease problem.

As a result, always allow time to elapse between each small adjustment before rechecking the temperature and making any further changes. Once the water has reached the required temperature, a relatively small amount of electricity is needed to maintain it at that level. An additional consideration is that the larger the aquarium is, the slower the rate of heat loss from it.

Most aquarium heaters are manufactured with standard ratings.  These ratings are usually in steps of 50 or 100 watts. Therefore, if you are using heaters inside the tank, it is more efficient to split the total heat requirements between two heater units positioned at opposite ends of the tank. Having 2 heaters will help maintain an even temperature distribution throughout the aquarium. It will also safeguard against sudden drops in temperature if one heater fails.